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Does knowing someone longer mean you know them better?

New research about to be published in the Journal of Consumer Psychology suggests that even though people claim to be pretty good at predicting the likes and dislikes of others, they are, in fact, anything but that. And, surprisingly, the longer we know someone, the worse our predictions may get.

…It turned out that everyone was able to better predict the likes and dislikes of someone they knew more than those of a complete stranger. But not that much better. Those asked to predict the preferences of people they had known for a short time were accurate 42 per cent of the time. And tellingly those who had known a person much longer were accurate only 36 per cent of the time.

There are a number of reasons why a longer standing relationship could lead to a reduced understanding of another’s likes and dislikes. Firstly, the majority of understanding and learning occurs in the early stages of relationships, when the motivation to get to know someone is much higher. Secondly, people who are in longstanding relationships often consider themselves to be more committed to each other and as a result may think that they know each other better than is actually the case. As a result they are less likely to notice changes in attitudes and preferences when they occur.